﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;

namespace BLL.Sec
{
    /// <summary>
    /// 加密、解密 类
    /// </summary>
    public class Crypt
    {
        #region 加密、解密函数
        /// <summary>
        /// DES加密函数
        /// </summary>
        /// <param name="pToEncrypt">原文</param>
        /// <param name="sKey">密钥(八位)</param>
        /// <returns>密文</returns>
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            if (sKey == null)
                sKey = "Metarnet";
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //把字符串放到byte数组中  
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);

            //建立加密对象的密钥和偏移量  
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            //Write  the  byte  array  into  the  crypto  stream  
            //(It  will  end  up  in  the  memory  stream)  
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //Get  the  data  back  from  the  memory  stream,  and  into  a  string  
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                //Format  as  hex  
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }
        /// <summary>
        /// DES解密函数
        /// </summary>
        /// <param name="pToDecrypt">密文</param>
        /// <param name="sKey">密钥(八位)</param>
        /// <returns>原文</returns>
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            if (sKey == null)
                sKey = "Metarnet";
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            //Put  the  input  string  into  the  byte  array  
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            //建立加密对象的密钥和偏移量，此值重要，不能修改  
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            //Flush  the  data  through  the  crypto  stream  into  the  memory  stream  
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();

            //Get  the  decrypted  data  back  from  the  memory  stream  
            //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象  
            StringBuilder ret = new StringBuilder();

            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }

        #endregion
    }
}
